package com.hd123.rumba.util;

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.util.Random;

/**
 * 创建一个人可阅读但难以被程序阅读的图片, 大小60x20, 由4位随机数字组成. 使用方法:<br>
 * 
 * HumanReadableImage hri = new HumanReadableImage();<br>
 * String content = hri.getContent();<br>
 * Image image = hri.getImage();<br>
 * //将认证码存入SESSION<br>
 * session.setAttribute("rand", sRand);<br>
 * //设置页面不缓存<br>
 * response.setHeader("Pragma","No-cache");<br>
 * response.setHeader("Cache-Control","no-cache");<br>
 * response.setDateHeader("Expires", 0);<br>
 * //输出图象到页面 <br>
 * ImageIO.write(image, "JPEG", response.getOutputStream());<br>
 * 
 * @author caili
 * 
 */
public class HumanReadableImage {
  private String sRand;
  private BufferedImage image;

  /**
   * 取得图片
   * 
   * @return
   */
  public BufferedImage getImage() {
    return image;
  }

  /**
   * 取得图片的字符内容
   * 
   * @return
   */
  public String getContent() {
    return sRand;
  }

  public HumanReadableImage() {
    // 在内存中创建图象
    int width = 60, height = 20;
    BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);

    // 获取图形上下文
    Graphics g = image.getGraphics();

    // 生成随机类
    Random random = new Random();

    // 设定背景色
    g.setColor(getRandColor(200, 250));
    g.fillRect(0, 0, width, height);

    // 设定字体
    g.setFont(new Font("Times New Roman", Font.PLAIN, 18));

    // 画边框
    // g.setColor(new Color());
    // g.drawRect(0,0,width-1,height-1);

    // 随机产生155条干扰线，使图象中的认证码不易被其它程序探测到
    g.setColor(getRandColor(160, 200));
    for (int i = 0; i < 155; i++) {
      int x = random.nextInt(width);
      int y = random.nextInt(height);
      int xl = random.nextInt(12);
      int yl = random.nextInt(12);
      g.drawLine(x, y, x + xl, y + yl);
    }

    // 取随机产生的认证码(4位数字)
    for (int i = 0; i < 4; i++) {
      String rand = String.valueOf(random.nextInt(10));
      sRand += rand;
      // 将认证码显示到图象中
      g.setColor(new Color(20 + random.nextInt(110), 20 + random.nextInt(110), 20 + random
          .nextInt(110)));
      // 调用函数出来的颜色相同，可能是因为种子太接近，所以只能直接生成
      g.drawString(rand, 13 * i + 6, 16);
    }

    // 图象生效
    g.dispose();
  }

  private Color getRandColor(int fc, int bc) {// 给定范围获得随机颜色
    Random random = new Random();
    if (fc > 255)
      fc = 255;
    if (bc > 255)
      bc = 255;
    int r = fc + random.nextInt(bc - fc);
    int g = fc + random.nextInt(bc - fc);
    int b = fc + random.nextInt(bc - fc);
    return new Color(r, g, b);
  }

}
